Since my first idea was fail, I decided to do one thats more... do-able. EarthQuake is a map that features a small town ravaged by an earthquake. Some buildings are in the half in the and others are just ruins. Streets have gone without repair. Vehicles are destroyed, and water is flooding. You should make the map with a few 3-room buildings, towers, walkways, and bridges. You should place the town near the beach.
This actually isn't a bad one (especially when compared to your impossible Pelican Crash idea) but it still brings about the same question. Why not do it yourself? People don't usually like to take other peoples ideas, that is unless the idea is so amazing that stealing it is almost irresistable, and people deffinetly don't like to give others credit. Just do it yourself.
From what I've seen, a partially ruined city would be relatively original. I've seen quite a few maps that have incorporated some level of urban design. Unfortunately, if one were to go with "flooding water", the map would be cursed by the over-used idea of submerging some or all of a map under the ocean in Forge World. However, this idea is much better and more doable than your last. I do agree with Hopeful in that I highly recommend you try this yourself. If you find out down the road that it isn't working out, or you are unable to finish, you can always put your progress up for adoption by other interested forgers.
I dont play X360 much, and I dont have Xbox Live yet. (I play PS3 most of the time. Uncharted 2 rocks yo.) I'm just passing around ideas until I can actually post them online. Just trying to help out the mapmakers, I guess.
You could put it all in the water with rocks as unflooded spots (where I live big ciities have few spots of natural grass. So yeah) and have blown up falcons (They're fail rescue vehicles) and a bunch of other stuff! I am sadly working on a map where people are trapped in a city with zombies....